In 2004, CBS News anchor Dan Rather was given a series of memos purporting to show how George W. Bush had avoided service in Vietnam during the early 1970s. Rather wanted so badly for the document to be real that he put it on the air without much thought. He even sexed up his sourcing a bit, claiming (falsely) that the documents had been authenticated by experts.

It took nearly two weeks for the fake documents to be exposed and for this highly damaging story about George W. Bush to be disproven. For most of that period, CBS News and Rather stridently defended their fake story, bringing further discredit upon the entire organization.

"Rathergate" was unique in its spectacular nature, but it was no isolated incident. It confirmed in conservatives' minds the unmistakable pattern that even when conservatives are right on the merits (which is often), they will not get a fair shake from a mainstream political media whose practitioners are overwhelmingly left wing and vote 80 to 90 percent Democratic in every presidential election. There are some in denial about this reality, but the body of evidence is large enough that I was able to fill an entire book with examples (by no means comprehensive) just from the recent election campaign.

Conservative distrust of the traditional media has created a relatively small but thriving market for alternatives, such as talk radio and Fox News. And more recently, conservatives have attempted to establish a foothold in the daily online media, both within traditional conservative institutions like National Review and Human Events, and from points beyond them.

I hope that this project succeeds. But it won't if conservative journalists are content to laugh at Dan Rather's demise without learning from his mistakes.

There are lessons in the recent Breitbart "scoop" about Chuck Hagel and his possible source of funding -- a group called "Friends of Hamas." Ben Shapiro, a prolific young writer who impressed everyone with his recent appearance on Piers Morgan's evening television show, wrote of this unsavory Hagel connection on Feb. 7, after hearing the group's name from an unnamed Senate staffer (to whom he referred in the plural). The problem is, the group doesn't exist.

The first reason this item should not have been published is that you just don't print things you don't know to be true. Rumors from anonymous sources often provide a starting point for tracking stories down, but they are not stories. Especially if they are damaging, they do not deserve to be dignified with a mention in print. And the more explosive the rumor, the more evidence is required to justify its publication.

But because we are talking about a conservative outlet, there is a second reason. An unwillingness to embrace basic standards is just the sort of thing that can torpedo conservative efforts in the print and online media. One cannot hold the mainstream media accountable by imitating its worst shortcomings.

Shapiro's Piers Morgan appearance demonstrated his smarts and talent as a spokesman for conservative ideas. All the more reason, then, to stop this embarrassing exercise of defending a bad mistake. We all make mistakes -- and we survive them by admitting it and moving on.

Shapiro has defended his story by noting he reported, accurately, that he was told something. This is technically true, but not a real defense for airing prejudicial information without knowing anything about its accuracy. Shapiro has also noted his original post was "clearly caveated" to demonstrate that he wasn't sure his source's information was correct. Perhaps this indicates that he didn't mean to deceive anyone, but that's a pretty low bar. What the caveat really proves is that the item should not have been published. If you have to warn your readers that you're not really sure whether your explosive revelation is true or not, it's a good sign you shouldn't be printing it.

And if the excuse for publishing a false rumor begins with the fact that the mainstream media "downplayed or ignored" Chuck Hagel's documented hostility toward the Israeli government or "the Jewish lobby" -- well, we're basically approaching "fake but accurate" territory here.

Conservative journalists should leave the rumor-mongering to Harry Reid and his imaginary friends. If anything, those on the Right must hold themselves to higher standards, because it's a given that they will receive no quarter for big mistakes like this one, nor even for smaller ones.

The crew at Breitbart has never accepted such behavior from liberal mainstream journalists in the past, nor should they in the future.

David Freddoso is The Washington Examiner's editorial page editor and author of the new book "Spin Masters: How the media ignored the real news and helped reelect Barack Obama" (Regnery, 2013).